The goal of various non-repudiation schemes is essentially to provide proof that a message has been sent and received. In many cases, a third party (e.g., a central authority or arbitrator) is used to verify time stamps and signatures that serve to document the interaction between a message sender and a message receiver. Sometimes additional parties, such as notaries, are used.
While several mechanisms to support non-repudiation have been developed, most of them load the network down with duplicative data transmission, and/or rely on extensive participation by the third party to the transaction. In addition, the third party may be burdened with storing and maintaining transaction records that will support verification efforts in the future, perhaps to resolve potential disputes.